Bunk bed



FIG. 1 is a front perspective view of a bunk bed, showing our new design;

FIG. 2 is a rear elevational view; and,

FIG. 3 is a top plan view thereof;

The undisclosed side of the bunk bed is a mirror image of the side shown in FIG. 1. 

The ornamental design for a bunk bed, as shown and described. 